The present invention relates to a semiconductor device and a method of manufacturing the same, which are suited for use, for example, in a semiconductor device equipped with a memory cell and a fuse.
SRAM (static random access memory) is one of semiconductor memories. A single SRAM memory cell is comprised of two access transistors, two drive transistors, and two load transistors. As one of SRAM, there is a SRAM having a thin-film transistor as two of these six transistors in order to achieve miniaturization and this SRAM is called “advanced SRAM”.
In the advanced SRAM, a lower interlayer insulating film covers access transistors and drive transistors and this lower interlayer insulating film has thereon a bit line and the like. An upper interlayer insulating film covers this bit line and the like. The upper interlayer insulating film has therein load transistors, which are thin-film transistors, and a capacitor. The upper interlayer insulating film has thereon predetermined wirings including a wiring for electrically coupling between memory cells and a wiring for electrically coupling a memory cell and a peripheral circuit. These predetermined wirings are made of, for example, aluminum or the like.
Memory cells of the advanced SRAM and the like are equipped with a fuse for switching a memory cell determined to be defective to a normal memory cell. This fuse is in a fuse portion placed around a memory cell portion. The fuse is formed as one of the predetermined wirings and is electrically coupled to a bit line extending from the memory cell or the like.
This means that in the fuse portion, the fuse and the bit line are electrically coupled to each other via a contact plug penetrating through the upper interlayer insulating film and the lower interlayer insulating film. Switching to a normal memory cell is made by exposing a predetermined fuse to a laser light to completely fusion-cut the fuse. This kind of fuse is especially called “LT (laser trimming) fuse”.
In the memory cells of the advanced SRAM or the like, not only switching of a memory cell determined to be defective to a normal cell but also switching of a power source or the like is performed using the fuse. Patent documents that have disclosed a semiconductor device equipped with a fuse are, for example, Patent Document 1 and Patent Document 2.
[Patent Document 1] Japanese Unexamined Patent Application Publication No. 2005-32916
[Patent Document 2] Japanese Unexamined Patent Application Publication No. 2000-294648